With rapid development of packet services and intelligent terminals, a high-speed service with a large data volume has an increasing requirement for spectrums. To meet a requirement that a downlink peak speed of a Long Term Evolution (Long Term Evolution, LTE for short) system of the 3rd Generation Partnership Project (The 3rd Generation Partnership Project, 3GPP for short) is 1000 Mbit/s, and an uplink peak speed is 500 Mbit/s, a maximum 100-megahertz transmission bandwidth needs to be provided. Because continuous spectrum resources of such a large bandwidth are scarce, a carrier aggregation (Carrier Aggregation, CA for short) solution is proposed. However, spectrum resources of a licensed frequency band of the LTE are limited, and according to the latest released Federal Communications Commission (Federal Communications Commission, FCC for short) international spectrum white paper, unlicensed spectrum (unlicensed spectrum) resources are more than licensed spectrum resources. Therefore, if the LTE is applied to an unlicensed frequency band, the unlicensed spectrum resources may be used more effectively, increasing an available spectrum bandwidth of an LTE user.
At present, there are many users sharing the unlicensed frequency band. These users may belong to different radio access technologies (Radio Access Technology, RAT for short), such as wireless fidelity (Wireless Fidelity, WiFi for short), Bluetooth (Bluetooth), and Zigbee (Zigbee). If the LTE uses the unlicensed frequency band in a carrier aggregation technology, the LTE needs to contend with another RAT user by using an appropriate channel contention mechanism, so as to reduce mutual interference, and fairly and properly use the unlicensed spectrum resources.